Study finds psychopaths have brain abnormalities

Scientists who scanned the brains of men convicted of murder, rape and violent assaults have found the strongest evidence yet that psychopaths have structural abnormalities in their brains.

The researchers, based at King's College London's Institute of Psychiatry, said the differences in psychopaths' brains separate them distinctly from other violent criminals with anti-social personality disorders (ASPD), and from healthy non-offenders.

Interest in what goes on inside the heads of violent criminals has been sharpened by the trial of Anders Behring Breivik, the Norwegian who massacred 77 people last July.

Two court-appointed psychiatric teams who examined Breivik came to opposite conclusions about his mental health. The killer himself wants to avoid an insanity finding, as he believes it would delegitimise his extremist cause.

Nigel Blackwood, who led the study, said the ability to use brain scans to identify and diagnose this sub-group of violent criminals had important implications for treatment.

The study showed that psychopaths, who are characterised by a lack of empathy, had less grey matter in the areas of the brain important for understanding other peoples' emotions.

Mr Blackwood's team used magnetic resonance imaging (MRI) to scan the brains of 44 violent adult male offenders in Britain who had already been diagnosed with anti-social personality disorders.

The crimes they had committed included murder, rape, attempted murder and grievous bodily harm.

Of the 44 men scanned, 17 met the diagnosis for ASPD plus psychopathy and 27 did not. The researchers also scanned the brains of 22 healthy non-offenders.

The results showed that the psychopaths' brains had significantly less grey matter in the anterior rostral prefrontal cortex and temporal poles than the brains of the non-psychopathic offenders and non-offenders.

These areas of the brain are important for understanding other people's emotions and intentions, and are activated when people think about moral behaviour, the researchers said.

Damage to these areas is linked with a lack of empathy, a poor response to fear and distress and a lack of self-conscious emotions such as guilt or embarrassment.

"We describe those without psychopathy as 'hot-headed' and those with psychopathy as 'cold-hearted'," Mr Blackwood explained.

"The 'cold-hearted' psychopathic group begin offending earlier, engage in a broader range and greater density of offending behaviours, and respond less well to treatment programs in adulthood compared to the 'hot-headed' group."

While cognitive and behavioural treatments may benefit people with anti-social personality disorders, the same approach may not work for psychopaths with brain damage, Mr Blackwood said.

"To get a clear idea of which treatments are working, you've got to clearly define what people are like going into the treatment programs," he said.

Essi Viding a professor in the psychology and language sciences department of University College London, who was not involved in Mr Blackwood's study, said it provided "weighty new evidence" about the importance of distinguishing psychopathic from non-psychopathic people rather than grouping them together.

The findings also have implications for the justice system, because linking psychopathy to brain function raises the prospect of arguing a defence of insanity.